How about:
a<-c("2001-02-1",NA,NA)
b<-c("2001-03-1","2001-03-2","2001-03-3")
res <- ifelse(is.na(a), as.character(as.Date(b)-2),
as.character(as.Date(a)))
res
Or with no ifelse:
res <- a
res[is.na(a)] <- as.character(as.Date(b[is.na(a)])-2)
res
Cheers,
Simon.
On Fri, 2008-02-08 at 14:23 +1300, Andrew McFadden
wrote:> Hi There
>
> I am a new user of "R" and having a few problems
>
> a<-c("2001-02-1","NA","NA")
> a<-as.Date(a,format = "%Y-%m-%d")
>
> b<-c("2001-03-1","2001-03-2","2001-03-3")
> b<-as.Date(b,format = "%Y-%m-%d")
>
> c<-data.frame(a,b)
>
> I would like to write an if statement where if "a" is not null
return
> "a", if "a" is null (NA) return "b" less two
days. Could someone help?.
>
>
> Andrew
>
>
>
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--
Simon Blomberg, BSc (Hons), PhD, MAppStat.
Lecturer and Consultant Statistician
Faculty of Biological and Chemical Sciences
The University of Queensland
St. Lucia Queensland 4072
Australia
Room 320 Goddard Building (8)
T: +61 7 3365 2506
http://www.uq.edu.au/~uqsblomb
email: S.Blomberg1_at_uq.edu.au
Policies:
1. I will NOT analyse your data for you.
2. Your deadline is your problem.
The combination of some data and an aching desire for
an answer does not ensure that a reasonable answer can
be extracted from a given body of data. - John Tukey.